CST

Photonic Crystal Simulation

Photonic crystals are periodic structures that are designed to affect the motion of photons in a similar way that periodicity of a semiconductor crystal affects the motion of electrons. The non-existence of propagating EM modes inside the structures at certain frequencies introduces unique optical phenomena such as low-loss-waveguides, omni-directional mirrors and others. The part of the spectrum for which wave propagation is not possible is called the optical band-gap.  The underlying physical phenomenon is based on diffraction. Therefore, the lattice constant of the photonic crystal structure has to be in the same length-scale as half the wavelength of the electromagnetic wave. Figure 1 shows a one dimensional periodic structure which is investigated by using the transient solver of CST MICROWAVE STUDIO® (CST MWS).


1 dimensional periodic structure
Figure 1: 1 dimensional periodic structure

The rods are made from GaAS with refractive index of 3.4 and with an edge length of about 180 nm. The lattice spacing between the rods is 760 nm. As a first step, the transmission of a plane wave through this crystal is simulated.


single column of the array
Figure 2: single column of the array

By using appropriate boundary and symmetry conditions it is sufficient to calculate a single column of this array as shown in Figure 2. In this case, the structure is driven by a waveguide port. Due to the magnetic and electric symmetry planes, the excitation mode is a  normally incident plane wave.


Transmisson vs. wavelength
Figure 3: Transmisson vs. wavelength

Figure 3 shows the transmission through the structure. Between 1400 and 2200 nm the transmission is zero. In this bandgap region no wave propagation in possible.


Wave Propagation at frequencies below the band gap
Figure 4: Wave Propagation at frequencies below the band gap

Figures 4-6 shows the propagation of a plane wave at normal incident for at different frequencies.


Wave propagation at frequencies in the band gap
Figure 5: Wave propagation at frequencies in the band gap


Wave Propagation at frequencies above the band gap
Figure 6: Wave Propagation at frequencies above the band gap

The information obtained about the photonic band gap can be used to design optical devices. Figure 7 shows the periodic PBG structure as described above. A line defect is introduced and the structure is excited with a electromagnetic wave at band gap frequencies. The wave can only propagate inside the line defect.


Photonic Crystal with line defect
Figure 7: Photonic Crystal with line defect

Finally, Figure 8 shows the wave propagation inside the Photonic crystal with a bent defect. Again, the structure is driven with a time harmonic signal. The signal frequency is inside band gap of the crystal. Consequently, the wave propagates inside bend defect.


Photonic crystal with a bend defect
Figure 8: Photonic crystal with a bend defect

This article demonstrates the possibilities to model photonic crystals with CST MWS by using the transient solver. The general characterization would also be possible with the Frequency Domain and Eigenmode Solver of CST MWS by applying periodic boundary conditions.


CST Article "Photonic Crystal Simulation"
last modified 15. Jan 2007 5:42
printed 20. Apr 2014 8:42, Article ID 296
URL:

All rights reserved.
Without prior written permission of CST, no part of this publication may be reproduced by any method, be stored or transferred into an electronic data processing system, neither mechanical or by any other method.

Feedback

5 of 10 people found this article useful

Did you find this article useful?

Other Articles

Consistent Charged Particle Simulation of a Pierce Gun

Consistent Charged Particle Simulation of a Pierce Gun
The pierce type gun example demonstrates the analysis of an electrically large gun configuration using CST PARTICLE STUDIO™ Read full article..

Modeling the susceptibility of enclosures to ESD and the effect of attaching cables

Modeling the susceptibility of enclosures to ESD and the effect of attaching cables
This webcast in the series discusses recent advances in modeling ESD generators using CST STUDIO. Direct transient analysis is used to simulate the ESD test waveforms defined by the IEC 61000-4-2 standard. We demonstrate the importance of modeling the physical geometry of the generator, including the ground strap. We simulate a direct contact discharge to an enclosure and predict the resulting current paths and radiated electromagnetic fields. Finally, we investigate the effect of attaching cables to the enclosure. Read full article..

Ku-Band Traveling Wave Tube

Ku-Band Traveling Wave Tube
This article describes the hot and cold test analysis of a traveling wave tube. Such a simulation uses a broad spectrum of the solvers available in CST STUDIO SUITE™. The complete simulation procedure is shown. First the electron gun is analyzed. Then the dispersion characteristics of the slow wave structure are evaluated. Finally the particle in cell (PIC) simulation of the beam inside the vacuum tube is performed. Read full article..

Power Integrity Simulation for High Speed Board using CST PCBS

Power Integrity Simulation for High Speed Board using CST PCBS
Power Integrity simulation for a high speed board, PCI-Express. using CST PCBS is shown here. The first simulation is the static power integrity simulation, known as IR-Drop. The second simulation is the high freq. power integrity simulation, whereas the decoupling capacitors are also taken into account to reduce the impedance of the board. Read full article..

EMI from Multi-Gigabit SerDes Differential Pairs

EMI from Multi-Gigabit SerDes Differential Pairs Document type
P. Sochoux, Cisco Video of an Innovations 2009 workshop series presentation. Read full article..
Back Back  

Your session has expired. Redirecting you to the login page...